Effects of age and genetic variations in VKORC1, CYP2C9 and CYP3A4 on the phenprocoumon dose in pediatric patients.

AIM: To study the effects of clinical and genetic factors on the phenprocoumon dose requirement in pediatric patients and to develop a dosing algorithm. METHODS: Pediatric patients who used phenprocoumon were invited to participate in a retrospective follow-up study. Clinical information and genotypes of genetic variations in CYP2C9, VKORC1, CYP4F2, CYP2C18 and CYP3A4 were collected and tested with linear regression for association with phenprocoumon dose requirement. RESULTS: Of the 41 patients included in the analysis, age, VKORC1, CYP2C9*2/*3 and CYP3A4*1B were statistically significantly associated with dose requirement, and together explained 80.4% of the variability in phenprocoumon dose requirement. CONCLUSION: Our study reveals that age and genetic variations explain a significant part of the variability in phenprocoumon dose requirement in pediatric patients.

Definition of insulin resistance affects prevalence rate in pediatric patients: a systematic review and call for consensus.

BACKGROUND: As a result of the rising prevalence of childhood obesity, there is an increasing interest in the type 2 diabetes mellitus precursor insulin resistance (IR). The aim of this study is to review definitions (methods and cutoff values) to define IR in children and to apply these definitions to a previously described obese pediatric population. METHODS: A systematic literature review on prevalence and/or incidence rates in children was performed. The extracted definitions were applied to an obese pediatric population. RESULTS: In the 103 identified articles, 146 IR definitions were reported based on 14 different methods. Fasted definitions were used 137 times, whereas oral/intravenous glucose tolerance test-derived methods were used nine times. The homeostasis model for the assessment of insulin resistance (HOMA-IR) and fasted plasma insulin (FPI) were the most frequently used fasted methods (83 and 37 times, respectively). A wide range in cutoff values to define IR was observed, resulting in prevalence rates in the predefined obese pediatric population between 5.5% (FPI>30 mU/L) and 72.3% (insulin sensitivity indexMatsuda≤7.2). CONCLUSIONS: To compare IR incidence and prevalence rates in pediatric populations, a uniform definition of IR should be defined.

Reporting of covariate selection and balance assessment in propensity score analysis is suboptimal: a systematic review.

OBJECTIVES: To assess the current practice of propensity score (PS) analysis in the medical literature, particularly the assessment and reporting of balance on confounders. STUDY DESIGN AND SETTING: A PubMed search identified studies using PS methods from December 2011 through May 2012. For each article included in the review, information was extracted on important aspects of the PS such as the type of PS method used, variable selection for PS model, and assessment of balance. RESULTS: Among 296 articles that were included in the review, variable selection for PS model was explicitly reported in 102 studies (34.4%). Covariate balance was checked and reported in 177 studies (59.8%). P-values were the most commonly used statistical tools to report balance (125 of 177, 70.6%). The standardized difference and graphical displays were reported in 45 (25.4%) and 11 (6.2%) articles, respectively. Matching on the PS was the most commonly used approach to control for confounding (68.9%), followed by PS adjustment (20.9%), PS stratification (13.9%), and inverse probability of treatment weighting (IPTW, 7.1%). Balance was more often checked in articles using PS matching and IPTW, 70.6% and 71.4%, respectively. CONCLUSION: The execution and reporting of covariate selection and assessment of balance is far from optimal. Recommendations on reporting of PS analysis are provided to allow better appraisal of the validity of PS-based studies.

CARING (CAncer Risk and INsulin analoGues): the association of diabetes mellitus and cancer risk with focus on possible determinants - a systematic review and a meta-analysis.

BACKGROUND: Patients suffering from diabetes mellitus (DM) may experience an increased risk of cancer; however, it is not certain whether this effect is due to diabetes per se. OBJECTIVE: To examine the association between DM and cancers by a systematic review and meta-analysis according to the PRISMA guidelines. DATA SOURCES: The systematic literature search includes Medline at PubMed, Embase, Cinahl, Bibliotek.dk, Cochrane library, Web of Science and SveMed+ with the search terms: "Diabetes mellitus", "Neoplasms", and "Risk of cancer". STUDY ELIGIBILITY CRITERIA: The included studies compared the risk of cancer in diabetic patients versus non-diabetic patients. All types of observational study designs were included. RESULTS: Diabetes patients were at a substantially increased risk of liver (RR=2.1), and pancreas (RR=2.2) cancer. Modestly elevated significant risks were also found for ovary (RR=1.2), breast (RR=1.1), cervix (RR=1.3), endometrial (RR=1.4), several digestive tract (RR=1.1-1.5), kidney (RR=1.4), and bladder cancer (RR=1.1). The findings were similar for men and women, and unrelated to study design. Meta-regression analyses showed limited effect modification of body mass index, and possible effect modification of age, gender, with some influence of study characteristics (population source, cancer- and diabetes ascertainment). LIMITATIONS: Publication bias seemed to be present. Only published data were used in the analyses. CONCLUSIONS: The systematic review and meta-analysis confirm the previous results of increased cancer risk in diabetes and extend this to additional cancer sites. Physicians in contact with patients with diabetes should be aware that diabetes patients are at an increased risk of cancer.